A technique of transferring genes to a cell as typified by micro-injection is the key to improving bleeding efficiency of animal and plant species and microbial species having useful characteristics. Thus, various transferring methods have been developed hitherto from the viewpoints of reliability and efficiency.
For example, the inventors of the present invention developed such technique that a microcapillary array where a number of injection probes are regularly arrayed, and a microchamber array having chambers corresponding to the probes are used to collectively inject DNAs to all cells held in the micro chamber array for the purpose of enhancing operation (see Patent Document 1). However, according to this method, it is difficult to sufficiently cover variations in shape, size, and elasticity between cells. In some cases, the injection probe cannot be inserted to a cell, or if inserted, the insertion depth is too small or large, with the result that DNAs cannot be collectively injected. Further, a probe insertion direction and a direction in which an observer observes a target portion with a microscope are substantially the same. This makes it difficult to insert a probe while observing a target portion with a microscope in practice. Even if the target portion can be observed with a microscope, a probe moves in a focal depth direction of the microscope, leading to a problem that an image is blurred due to the movement and its positional control is difficult.
To that end, the inventors of the present invention have made extensive studies in view of operational reliability and developed a microchannel array capable of suction trap of cells or other such particles at an opening edge of a substrate end surface (see Patent Document 2). If the microchannel array is used, during micro-injection, the probe movement direction and the observation direction of the microscope are substantially orthogonal to each other, so the injection can be carried out while observing with the microscope. Thus, DNA or other such substances can be more reliably and readily injected.
However, the above microchannel array has a possibility that cells are damaged upon suction trap of the cells. Further, although the microchannel array is suitable for micro-injection, the array is inappropriate for incubation of cells prior to the injection or differentiation/proliferation of cells after the injection. Thus, it is necessary to culture cells in another place prior to the injection, and to carry out differentiation/proliferation of cells in another place after the injection, resulting in a problem that the total efficiency of the operation is low. Another serious problem is that a cell differentiation/proliferation speed cannot be increased.    [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2000-23657    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2002-27969